In his wonderful book, "Founding Brothers," historian Joe Ellis says of the American Revolution that "no event in American history, which was so improbable at the time, has seemed so inevitable in retrospect."

As we think back on the rightness of America's cause, we find it hard to believe that it could have come out any other way.

Yet, as Ellis writes, when the Declaration of Independence was signed, the signers had no idea how the revolution would end. The most likely outcome was failure.

No matter the rightness of the cause, the signers were defying the most powerful nation in the world, and no colony had ever successfully broken away from a mother country.

Revolution after revolution against imperialist powers followed ours, but until ours, none had succeeded.

All the signers of our declaration knew for certain was that if it failed, they would hang. Somehow, they won.

On the Fourth of July, we celebrate (as we should) the wisdom and the vision of the founders and the way, in one document, that Thomas Jefferson summarized the aspirations of all people: the right to life, liberty, and the pursuit of happiness.

But let us never forget the one thing that made all the rest of it and what came after it possible: courage - the courage of those who bet their very lives on a project that all signs suggested would fail.